Theoretical Investigation of Pressurised Thermal Shock in Rossendorf Coolant Mixing Model
Injection of Emergency Core Cooling (ECC) water during a Loss-Of-Coolant Accident (LOCA) into the cold leg of Pressurized Water Reactor (PWR) leads to Pressurised Thermal Shock (PTS) in the Reactor Pressure Vessel (RPV). When the injected ECC water comes in contact with the RPV wall, it results in large temperature gradient leading to large thermal stresses. Theoretical investigation is carried out to compare with the experimental data generated in Rossendorf Coolant Mixing Model (ROCOM). ROCOM is a 1:5 scaled German KONVOI type reactor having four-loop with a RPV mock-up made of transparent acrylic material. The reliable estimation of the thermal loads requires accurate prediction of the local and spatial mixing phenomena in the cold leg and downcomer which can be realised in CFD simulations. CFD analysis for buoyancy driven mixing with a constant flow rate in one loop and 10% density difference between the ECC injection and loop water was chosen to study PTS behaviours. The main objective of present work is to validate CFD code "OpenFOAM" with the available experimental data of PTS test due to buoyancy driven mixing phenomena. Effect of grid size and turbulence models has also been studied. The predicted results of CFD analysis have been compared with experimental data in upper downcomer and at the core inlet planes. It shows that results are in good agreement.